Our primary objective is to obtain experimental values of the Zimm-Bragg growth and nucleation parameters, s and sigma, for each of the 20 naturally occurring amino acids. These parameters characterize, in a quantitative way, the tendency of each amino acid residue in a protein to adopt an alpha-helical or a coil conformation. These experimental values of s and sigma will then be used to analyze the conformational properties of proteins. The parameters themselves are being obtained by studying the helix-coil transition of random copolymers of two types of amino acid, a host (whose s and sigma values are known) and a guest (whose s and sigma values are to be determined). Random copolymers of varying chain length and of varying composition of the host and guest residues are being synthesized and fractionated; melting data are being obtained for these fractions. Appropriate theory is now available for analyzing such experimental data. BIBLIOGRAHIC REFERENCES: Maxfield, Alter, Taylor and Scheraga -Helix-Coil Stability Constants for the Naturally Occuring Amino Acids in Water. IX. Glutamic Acid Parameters from Random Poly(hydroxybutylglutamine-co-L-glutamic acid), Macromolecules, 8, 479 (1975). Maxfield and Scheraga - The Effect of Neighboring Charges on the Helix Forming Ability of Charged Amino Acids in Proteins, Macromolecules, 8, 491 (1975).